The present invention relates to an electron tube which includes cathode linear members (e.g. cathode filaments), linear members (e.g. wire grids), getter linear members, and support auxiliary members (e.g. linear spacers and linear dampers), and to a method of manufacturing the same.
A fluorescent luminous tube, being one of conventional electron tubes, will be explained below by referring to FIGS. 12 and 13.
FIG. 12(a) is a plan view illustrating a glass substrate on which cathode filaments, a linear spacer, a linear damper, and others are mounted. FIG. 12(b) is a cross-sectional view of the portion taken along the line X1-X2 in FIG. 12(a). FIG. 12(c) shows another example of the structure in FIG. 12(b).
Referring first to Figs. 12(a) and 12(b), numeral 91 represents a glass substrate; 93 represents a cathode filament being a linear member; 951 represents a spacer (an auxiliary linear member) for supporting the filament 91; and 952 represents a damper (an auxiliary linear member) for supporting the filament 93.
One end of the filament 93 with the coil 931 is welded, together with the metal piece 921, to a metal layer 92 (acting as a cathode mounting electrode), vapor-deposited on the substrate 91. Using the linear (or rod-like) insulating (or glass) spacer 951, a filament 93 is suspended so as to be elevated by a predetermined interval from the anode 96 (e.g. an anode electrode) on which a fluorescent substance is coated. To prevent the filament 93 from being contacted with the anode 96 due to vibration, a damper 952 (of the same material as the spacer 951) is disposed on the substrate 91. The spacer 951 and the damper 952 are directly bonded to the substrate 952 or are adhered to the insulating layer of the substrate 91 using an adhesive agent (e.g. fritted glass).
Referring to FIG. 12(c), a conductive spacer 951 is securely adhered to the metal layer 941 bonded on the substrate 91, using a conductive paste. Some spacers 951 are formed of a conductive material entirely or of an insulating material (e.g. glass) coated with a conductive material.
FIG. 13 shows an example of a grid formed of a metal wire, that is, the so-called wire grid. FIG. 13(a) is a plan view partially illustrating a glass substrate on which a wire grid is mounted. FIG. 13(b) is a cross-sectional view partially illustrating the portion taken along the line X2xe2x80x94X2 of FIG. 13(a). Like reference numerals are attached to the same constituent elements as those in FIG. 12.
Referring to Fig. 13, numeral 97 represents a wire grid being a linear member; 953 represents a spacer being an auxiliary linear support member of the wire grid 97; and 954 represents a damper being an auxiliary linear support member of the wire grid 97.
The wire grid 97 is suspended between a cathode filament 93 and an anode 96 in the direction perpendicular to the filament 93. The linear (or rod-like) spacer 953 of an insulating material (e.g. glass) holds the wire grid 97 at a predetermined elevation. One end of the wire grid 97 is securely bonded using the substrate 91 and the side plate 912. In order to prevent the wire grid 97 from being contacted with the anode 96 due to vibration, the damper 954 of the same material as the spacer 953 is mounted on the substrate 91. The spacer 953 and the damper 954 are directly bonded to the substrate 91 or are adhered to an insulating layer overlying the substrate 91 using an adhesive agent (e.g. fritted glass).
Conventionally, an adhesive agent (e.g. fritted glass or an adhesive paste) has been used to securely bond the auxiliary liner support members (e.g. spacers and dampers). However, the problem is that gas is generated from the adhesive agent inside an electron tube (such as a fluorescent display), thus decreasing the vacuum degree therein.
In order to mount and bond the spacer or damper on a base (or a substrate), an adhesive agent such as fritted glass is heated, softened, cooled and solidified. However, when the adhesive agent is re-heated and softened in the post step, the spacer or damper is often separated or displaced. For that reason, a suitable adhesive agent has to be chosen in consideration of the steps after bonding spacers and dampers. The temperature after the bonding has to be controlled carefully. Hence, the step of mounting spacers and dampers is troublesome and leads to high manufacturing costs. The substrate, the adhesive agent, the spacer, and the damper are required to have the same thermal expansion coefficient. The choice of such materials is limited.
The conventional linear or rod-like spacer, which has a smooth surface, often causes displacement of a liner member (such as a cathode filament or a wire grid). To prevent the displacement, some spacers have a recessed formed on the surface thereof and a filament or a wire grid is disposed in the recessed. However, this approach leads to an increase of the fabrication costs of a spacer.
The present invention is made to solve the above-mentioned problems.
An object of the invention is to provide an electron tube wherein auxiliary support members (e.g. spacers and dampers) used to subsidiarily support liner members (e.g. cathode filaments and wire grids) are bonded to a substrate, without using an adhesive agent. This structure can reduce the generation of gas causing a decrease in vacuum degree and simplify the process of mounting the auxiliary support member.
Particularly, the ultrasonic welding (ultrasonic bonding or ultrasonic wire bonding) can be preferably performed to heat a local area, that is, only the contact surface (interface) between the metal layer and the auxiliary metal support.
The objective of the present invention is achieved by an electron tube comprising a hermetic container having a first substrate on which an anode is formed and a second substrate confronting the first substrate; a metal layer formed inside the hermetic container; a linear member disposed in the hermetic container so as to confront the metal layer; at least one set of holders, disposed in the hermetic container, for holding the linear member; and metal auxiliary members, disposed between the linear member and the metal layer, each for supporting a linear member welded to the metal layer.
In the electron tube, the linear member comprises a cathode filament. Each of said auxiliary members comprises a spacer for a cathode filament. At least one set of the spacers is disposed between (inside) the holders.
In the electron tube, the linear member comprises a cathode filament. Each of the auxiliary members comprises a spacer for a cathode filament. The metal layer comprises a cathode mounting electrode.
In the electron tube, the linear member comprises a cathode filament. Each of the auxiliary members comprises a damper for a cathode filament. The damper is disposed between (inside) the holders.
In the electron tube, the linear member comprises a cathode filament. The auxiliary members comprise a spacer and a damper, for a cathode filament. At least one set of spacers is disposed between (inside) the holders. At least one damper is disposed between (inside) the spacers.
In the electron tube, the linear member comprises a wire grid. Each of the auxiliary members comprises a spacer for the wire grid. At least one set of spacers is disposed between (inside) the holders.
In the electron tube, the linear member comprises a grid wire. Each of the auxiliary members comprises a damper for the wire grid. The damper is disposed between (inside) the holders.
In the electron tube, the auxiliary members are disposed independently for each linear member.
In the electron tube, the welding is ultrasonic welding.
In the electron tube, the metal layer and the auxiliary members are made of the same metal material.
In the electron tube, the metal layer comprises a thin film layer.
In the electron tube, the linear member has partially or wholly a spring for providing tension.
In the electron tube, the linear member comprises a linear spacer or a linear damper or a linear getter.
In the electron tube, the each of auxiliary members has a recessed or a protrusion at a position where each auxiliary member confronts a linear member.
In the electron tube, the electron tube is a fluorescent luminous tube.
According to another aspect of the present invention, a method of manufacturing an electron tube having a hermetic container containing a first substrate and a second substrate confronting said first substrate, comprising the steps of forming a metal layer inside the hermetic container; bonding a metal auxiliary member for linear member support to the metal layer, through ultrasonic welding; and disposing a linear member so as to confront the auxiliary member.
The electron tube manufacturing method further comprises the steps of forming an electrode on the substrate; and simultaneously forming the metal layer in the step, together with the electrode.
In the electron tube manufacturing method, the electrode comprises an anode electrode. The step is the step of manufacturing an anode electrode.
In the electron tube manufacturing method, the cathode comprises a cathode mounting electrode. The step is the step of manufacturing a cathode mounting electrode.
In the electron tube manufacturing method, the electron tube comprises a fluorescent luminous tube.